The showdown in Washington is the latest attempt by Trump to test the boundaries of his legal authority to carry out his tough-on-crime agenda, relying on obscure statutes and a supposed state of emergency to speed up the mass deportation of people in the United States illegally.

The influx came the morning after the Republican president announced he would be activating the guard members and taking over the District’s police department, something the law allows him to do temporarily.

Washington DC Mayor Muriel Bowser, a Democrat, who has denied crime is out of control in her city, described the troop deployment as an "authoritarian push". Trump, a Republican, has also threatened similar deployments against New York and Chicago, two other Democratic-controlled cities.